1. Field of the Invention
The present invention relates in general to distance measurement using a light beam, and more particularly to an optical distance measurement apparatus and method in which a distance to an object can be measured with no contact using a light beam by measuring a pure light moving time precisely, so that they are applicable to various distance measurements including a distance measurement of a car collision prevention system.
2. Description of the Prior Art
Conventional distance measurement equipments are mostly adapted to measure distances to objects relatively using standard measurement devices with corresponding lengths.
Such a conventional distance measurement equipment utilizes trigonometry for the distance measurement. For this reason, the conventional distance measurement equipment needs a relative measurement device with a length corresponding to the distance to be measured, or many measurement devices to calculate the distance. As a result, the conventional distance measurement equipment is complex in construction. In particular, it is impossible to install the conventional distance measurement equipment in a car for the purpose of measuring continuously the distance traveled by of the car.
To solve the above problems, there have been proposed optical distance measurement apparatus. Such a conventional optical distance measurement apparatus measures a light moving time and then the distance to the object on the basis of the measured light moving time and a light velocity. Precision in the distance measurement is dependent on accuracy in the light moving time measurement. However, since a light beam moves 30 cm for 1 nsec, it is very hard to measure accurately the light moving time.
Also, the conventional optical distance measurement apparatus is adapted to emit a pulse light beam to the object, convert a light beam reflected from the object into an electrical signal, and amplify the converted electrical signal, so as to measure the light moving time using the amplified electrical signal. Here, the pulse light beam is emitted to the object by light emitting means and the light beam reflected from the object is received by light receiving means. Noticeably, an intensity of the pulse light beam emitted from the light emitting means is rapidly reduced as the distance to the object is increased, thereby causing the reflected light beam received by the light receiving mean to be rapidly reduced in amount. Also, the light receiving means must detect a peak point of the pulse light beam, emitted from the light emitting means, for the distance measurement. For this reason, a distance error is generated in emitting and receiving the pulse light beam. Further, in the case where amplification of the same degree is applied for every distance, a measurable range of the distance is very short or the distance measurement cannot be performed.